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Abstract

The cyanide ion and its gaseous form, hydrogen cyanide, are extremely toxic. Cyanide impairs cellular respiration by inhibiting cytochrome c oxidase, an enzyme in the electron transport chain, leading to cell death.

In a previous study, we synthesized an optical sensor that detects cyanide selectively. The aim of this project is to increase the sensitivity of this sensor. This can be achieved by utilizing the unique spectroscopic properties of lanthanide ions.

The lanthanide metal (europium or terbium) was added to a coumarin-glycine chemodosimeter in a DMSO solvent system. The sensor was titrated with several monodentate analytes including, nitrate, octylamine, 1-pentanethiol, tetrafluoroborate, thiocyanate, azide, cyanide, and the halides, and several bidentate analytes including, acetate, phosphate monobasic, sulfate, ethylene diamine, 1,10-phenanthroline, carbonate, and citrate, using fluorescence and phosphorescence techniques.

The results from the fluorescence and phosphorescence studies show that the anions are not only coordinating to the coumarin sensor side of the molecule but are also directly coordinating to the lanthanide ion. This is problematic because it affects the sensitivity of the molecular probe. Thus, we carried out a series of studies by “blocking” the coordination environment of the lanthanide ion with different functional groups (aliphatic and aromatic amines) in order to force the cyanide ion to coordinate only to the coumarin molecule. Aliphatic amines initiate a lanthanide emission, but aromatic amines continue to quench the system.

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